Method for a code division multiple access telecommunication system

ABSTRACT

A method for a Code Division Multiple Access telecommunication system implemented by a mobile station. The Code Division Multiple Access telecommunication system implementing a phase of communicating data conveyed by a plurality of transport channels. The Code Division Multiple Access telecommunication system includes at least one base station and at least the mobile station with the mobile station performing a plurality of rate matching steps. Each of the rate matching steps executing a transformation of an input block of an initial size into an output block of a final size by puncturing or repeating at least one bit of the input block.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a division of application Ser. No.11/392,507, filed on Mar. 30, 2006; which is a continuation ofapplication Ser. No. 10/772,237, filed on Feb. 6, 2004; which is adivision of Ser. No. 10/359,705, filed on Feb. 7, 2003; which is adivision of Ser. No. 09/930,469, filed on Aug. 16, 2001; and which is adivision of Ser. No. 09/553,064, filed on Apr. 20, 2000, which claimspriority to French Application No. 99 05047, filed on Apr. 21, 1999 andFrench Application No. 99 08041, filed on Jun. 23, 1999, the entirecontents of each of which is incorporated herein by reference.

The present invention relates to a method for a Code Division MultipleAccess telecommunication system.

1. Discussion of the Background

The 3GPP (3^(rd) Generation Partnership Project) group is an associationwhose members originate from several regional standardization bodiesincluding in particular the ETSI (European TelecommunicationStandardization Institute) and the ARIB (Association of Radio Industriesand Businesses). Its object is the standardization of a third-generationtelecommunication system for mobiles. One of the fundamental aspectsdistinguishing third-generation from second-generation systems is that,apart from the fact that they will use the radio spectrum moreefficiently, they will allow very great flexibility of service.Second-generation systems offer an optimized radio interface for certainservices. For example GSM (Global System for Mobiles) is optimized forthe transmission of speech (telephony). Third-generation systems willoffer a radio interface adapted for all kinds of services andcombinations of services.

One of the issues at stake with third-generation mobile radio systems isthat of efficiently multiplexing, on the radio interface, services whichdo not have the same demands in teams of quality of service (QoS).Quality of service is defined, conventionally, according to at least onecriterion comprising in particular a processing delay, a bit error rateand/or an error rate per transported block. These different qualities ofservice require corresponding transport channels having differentchannel codings and channel interleavings. Moreover, they demanddifferent maximum bit error rates (BER). For a given channel coding, thedemand with regard to the BER is satisfied when the coded bits have atleast a certain coding-dependent ratio Eb/I. The ratio Eb/I expressesthe ratio of the average energy of each coded bit to the average energyof the interference.

It follows that the different qualities of service do not have the samedemand in terns of the ratio Eb/I. Now, in a system of the CDMA (CodeDivision Multiple Access) type, the capacity of the system is limited bythe level of interference. It is therefore necessary to fix the ratioEb/I as correctly as possible for each service. Therefore, a ratematching operation, for balancing the ratio Eb/I is necessary betweenthe various services. Without this operation the ratio Eb/I would befixed by the service having the greatest demand, and as a result theother services would have “too good” a quality, thereby impactingdirectly on the capacity of the system.

This raises a problem since it is necessary in some manner that the ratematching ratios be defined identically at the two ends of the radiolink.

The present invention relates to a configuring method for defining ratematching ratios identically at the two ends of a CDMA radio link.

In the OSI model (Open System Interconnection) from the ISO(International Standardization Organization), a telecommunicationequipment is modelled by a layered model constituting a stack ofprotocols where each level is a protocol supplying a service to thelevel above. Level 1 is in particular responsible for implementingchannel coding and channel interleaving. The service supplied by level 1is referred to as “transport channels”. A transport channel allows thehigher level to transmit data with a certain quality of service. Thequality of service is in particular characterized by the delay and theBER.

In order to satisfy the quality of service demand, level 1 uses acertain encoding and a suitable channel interleaving.

The known solutions, and in particular those proposed in the 3GPPproject, will be described with regard to FIGS. 1 and 2.

FIG. 1 is a diagrammatic view illustrating the multiplexing of thetransport channels on the uplink in the current 3GPP proposal;

FIG. 2 is a diagrammatic view illustrating the multiplexing of thetransport channels on the downlink in the current 3GPP proposal.

Represented in FIGS. 1 and 2 are the block diagrams for interleaving andmultiplexing as defined by the current proposal by the 3GPP group,although this proposal has not yet been finalized.

In these figures, similar blocks bear the same numbers. In both casesthe uplink (from the mobile station to the network) may be distinguishedfrom the downlink (from the network to the mobile station), and only thetransmission part is represented.

Each transport channel, labelled 100, periodically receives a transportblocks set from an higher level, labelled 102. The number of transportblocks 100 in this set, as well as their sizes, depend on the transportchannel. The minimum period at which the transport blocks set issupplied corresponds to the time span of the interleaving of thetransport channel. The transport channels with one and the same qualityof service (QoS) are processed by one and the same processing chain103A, 103B.

In each of the processing chains 103A, 103B, the transport channels, inparticular after channel encoding and channel interleaving, aremultiplexed together by concatenation in step 104. This multiplexing iscarried out per multiplexing frame. A multiplexing frame is the smallestunit of data for which demultiplexing may be carried out at leastpartially. A multiplexing frame typically corresponds to a radio frame.The radio frames form consecutive time intervals synchronized with thenetwork, and numbered by the network. In the proposal by the 3GPP group,a radio frame corresponds to a duration of 10 ms.

The 3GPP proposal comprises the service-specific coding and interleavingoption represented diagrammatically at 103C. The possibility of such anoption is being considered at present since its indispensability orotherwise has not yet been determined.

In the general case, a processing chain 100A firstly comprises a step106 during which a bit word termed the FCS (Frame Check Sequence) isattached to each transport block. The bit word FCS is typicallycalculated by the so-called CRC technique (Cyclic Redundancy Check)which consists in considering the bits of the transport block to be thecoefficients of a polynomial P and in calculating the CRC from theremainder of the polynomial (P+P0) after dividing by a so-calledgenerating polynomial G, where P0 is a predefined polynomial for a givendegree of P. The attachment of the bit word FCS is optional, and certaintransport channels do not include this step. The exact technique forcalculating the bit word FCS also depends on the transport channel, andespecially on the maximum size of the transport blocks. The usefulnessof the bit word FCS is in detecting whether the transport block receivedis valid or corrupted.

The next step 108 consists in multiplexing together the transportchannels (TrCH) of like quality of service (QoS). This is because thosetransport channels which have the same quality of service may use thesame channel coding. Typically, the multiplexing at 108 is carried outby concatenating the transport blocks sets with their FCS for eachtransport channel.

The next step, labelled 110, consists in performing the channelencoding. On exit from the channel encoder 110 there is a set of codedblocks. Typically, in the case of a convolutional code, we have eitherzero or a single coded block of variable length. The length is given bythe formula:N _(output) =N _(input)/(coding rate)+N _(tail)(length of the codedblock).with:

-   -   N_(output)=number of bits at output (length of the coded block);    -   N_(input)=number of bits at input;    -   coding rate=constant ratio; and    -   N_(tail)=fixed quantity of information, independent of        N_(input), serving to empty the channel decoder cleanly at the        time the coded block is received.

It is onwards of this step 110 that the uplink differs from thedownlink.

In each transport channel, whether the uplink (FIG. 1) or the downlink(FIG. 2), a rate matching step is implemented after the channel encodingstep 110. This step is labelled 112 for the uplink and 114 for thedownlink. Rate matching is not necessarily performed immediately afterchannel encoding 110.

The objective of the rate matching step 112 or 114 is to balance theratio Eb/I between the transport channels with different qualities ofservice. The ratio Eb/I gives the average energy of a bit with respectto the average energy of the interference. In a system using multipleaccess CDMA technology, the greater this ratio the greater is thequality which may be obtained. It will be understood therefore thattransport channels having different qualities of service do not have thesame need in terms of Eb/I, and that in the absence of rate matching,certain transport channels would have “too” good a quality of servicerelative to their respective needs, fixed as it is by the most demandingchannel in terms of quality of service. Such transport channels wouldthen needlessly cause interference. Rate matching therefore has a roleof matching the Eb/I ratio. Rate matching is such that X bits at inputgive Y bits at output, thus multiplying Eb/I by the ratio Y/X, hence thematching capability. In what follows, the ratio Y/X is referred to asthe rate matching ratio, also known as the rate matching ratio.

Rate matching is not done in the same way in the uplink and in thedownlink.

This is because, in the uplink, it has been decided to transmitcontinuously, since discontinuous transmission worsens the peak/averageratio of the radio-frequency power at the output of the mobile station.The closer this ratio is to I the better. This is because, if this ratiois worsened (that is to say increased), this signifies that the poweramplifier requires a greater margin (backoff) of linearity with respectto the mean operating point. On account of such a margin, the poweramplifier would be less efficient and would therefore consume more forthe same average power emitted, and this would in particularunacceptably reduce the mobile station's battery-powered endurance.Because it is necessary to transmit continuously on the uplink, the ratematching ratio Y/X cannot be constant. This is because the sum Y₁+Y₂+ .. . Y_(k) of the numbers of bits after matching must be equal to thetotal number of bits in the radio frame for the data. This number maytake only certain predefined values N₁, N₂, . . . , N_(p). It istherefore appropriate to solve the following system in k unknowns Y₁, .. . , Y_(k):

Input data: X_(i) number of bits at input Y_(i) number of bits at outputN_(pr) = |Y_(i) − X_(i)| number of bits to be repeated or to bepunctured (if Y_(i) > X_(i) we repeat, otherwise we puncture) Thepuncturing/repetition rule is as follows: e = 2*N_(p/r) − X_(i) initialerror between the current and desired puncture/repetition ratios x = 0index of the current bit while x < X_(i) do

else e = e + 2*N_(p/r) update the error end_if x = x + 1 next bit end_dowhere X_(i) and Eb_(i)/I and P_(i) are characteristic constants of eachtransport channel, and where it is sought to minimize N_(j) from amongthe p possible values N₁, N₂, . . . , N_(p) (note: P_(i) is the maximumallowable puncture rate for a coded transport channel).

Thus, in the uplink, the rate matching ratios Y/X for each transportchannel are not constant from one multiplexing frame to the next, butare defined to within a multiplicative constant: the pairwise ratiosbetween these ratios therefore remain constant.

In the downlink, the peak/average ratio of the radio-frequency power isin any case very poor since the network transmits to several userssimultaneously. The signals destined for these users combineconstructively or destructively, thereby inducing wide variations inradio-frequency power emitted by the network, and hence a poorpeak/average ratio. It was therefore decided that for the downlink thebalancing of Eb/I between the various transport channels would be donewith a rate matching having a constant rate matching ratio Y/X, and thatthe multiplexing frames would be supplemented with dummy bits, that isto say bits which are not transmitted, that is to say discontinuoustransmission.

Thus, the difference between the uplink and the downlink lies in thefact that in the uplink the rate matching 112 is dynamic so as tosupplement the multiplexing frames, whereas in the downlink the ratematching 114 is static and the multiplexing frames are supplementedthrough the insertion of dummy bits in the immediately following step124.

The rate matching, whether dynamic or static, is done either byrepetition or by puncturing, according to an algorithm which wasproposed to the ETSI by the Siemens Company (registered trade mark) inthe technical document referenced SMG2/UMTS-L1/Tdoc428/98. Thisalgorithm makes it possible to obtain non-integer puncture/repetitionratios, and it is given in Table 1 for information.

TABLE 1 Repetition or puncturing algorithm Input data: X_(i) - number ofbits at input Y_(i) - number of bits at output N_(pr=)|Y_(i)−X_(i)| -number of bits to be repeated or to be punctured (ifY_(i)>X_(i) werepeat, otherwise we puncture) The puncturing/repetition rule is asfollows: e=2*N_(p/r)−X_(i) -- initial error between the current anddesired puncture/repetition ratios x = 0 -- index of the current bitwhile x<X_(i) do if e > 0 then --test whether bit number x should berepeated/punctured {open oversize bracket} puncture or repeat bit numberx e = e + (2*Npir− 2* X;) --update the error else e = e + 2*Np/r --update the error end_if x = x + 1 --next bit - end_do

The particular feature of this algorithm is that, when it operates inpuncture mode, it avoids the puncturing of consecutive bits, but on thecontrary tends to maximize the spacing between two punctured bits. Asfar as repetition is concerned, the repetition bits follow the bitswhich they repeat. Under these conditions, it will be understood that itis beneficial for the rate matching to be done before interleaving. Thisis because, for repetition, the fact that an interleaving follows therate matching makes it possible to space the repeated bits apart. Forpuncturing, the fact that an interleaver precedes the rate matchinggives rise to the risk that the rate matching might puncture consecutivebits on exit from the channel encoder.

It is therefore advantageous for the rate matching to be done as high upas possible, that is to say as close as possible to the channel encoder.

Moreover, each processing chain 103A, 103B also comprises, after thechannel encoding step 110, a first interleaver labelled 116 for theuplink and 118 for the downlink, followed by a step of segmentation permultiplexing frame labelled 120 for the uplink and 122 for the downlink.The first interleaver 118 is not necessarily located immediately afterthe channel encoding 110.

For the downlink, it is possible to place the rate matching 114 right atthe output of the channel encoding 110, since the rate matching ratio isconstant. Hence, a priori only a single interleaver 118 is needed.

However, a second interleaver 136 is necessary, since the multiplexingof the transport channels of different qualities of service QoS is doneby straight-forward concatenation, and since such a method would in factlimit the time span of each multiplexed block.

For the uplink the rate matching ratio may vary with each multiplexingframe. This explains the need for at least the first interleaver 116before the rate matching 112 so as to distribute the bits of the codedblock over several multiplexing frames, and for a second interleaver 128placed after the rate matching so as to space apart the bits repeated bythe rate matching 112.

Thus in the block diagrams of FIGS. 1 and 2 may be seen two interleaversreferred to in the block diagrams as the first and second interleavers.The first interleaver 116, 118 is an interleaver whose time span isequal to the interleaving time span for the corresponding transportchannel. This span may be longer than the duration of a multiplexingframe and is typically a multiple thereof in a constant ratio. This iswhy this first interleaver 116, 118 is also sometimes referred to as aninter-frame interleaver.

The second interleaver 126, 128 is also referred to as an inter-frameinterleaver since its time span is that of a multiplexing frame.

Consequently the step of segmentation per multiplexing frame labelled120, 122 is situated between the first 116, 118 and the second 128, 126interleavers (when there is a second interleaver). This step consists insegmenting the blocks which are coded and are interleaved by the firstinterleaver into as many segments as is equal to the ratio of the timespan of the first interleaver to the duration of a multiplexing frame.This segmentation is typically done in such a way that the concatenationof the segments once again yields the interleaved coded block.

It will be noted that, in the uplink, this segmentation step 120 isnecessarily located before the rate matching 112. This is because therate matching 112 is done according to a ratio established dynamicallymultiplexing frame by multiplexing frame, and it is not thereforepossible to do it on a unit of data which may extend over severalmultiplexing frames.

In the uplink and the downlink, a step 130 of segmentation into physicalchannels is implemented before each second interleaver 126, 128.Likewise, the second interleavers 126, 128 are followed by a step 132 ofphysical channel mapping for transmission proper.

At present, only the multiplexing, channel encoding, interleaving andrate matching algorithms are defined and discussed. There is no rulemaking it possible to fix the way in which with a size X of a blockinput into the bit rate matcher there is associated a size Y of theblock obtained on output. We are reduced to assuming that all thecombinations of the pairs (X, Y) are predefined and saved in memory in afrozen manner. Only one of the following two things is possible:

-   -   either the set of pairs (X, Y) remains frozen and no flexibility        of definition of this set of pairs (X, Y) for the service        concerned is obtained, which is contrary to the sought-after        effect;    -   or the set of pairs (X, Y) is negotiated between the mobile        stations and the telecommunication network involved and a high        number of signalling bits and hence additional immobilization of        resources has to be envisaged.

A rule for determining the size Y of a rate matched block which is ratematched with the other blocks, on the basis of the size X of this blockbefore rate matching is necessary at least in the uplink. This isbecause, since the services have variable bit rates, the number oftransport blocks provided for each transport channel is variable. Thelist (X₁, X₂, . . . , X_(k)) of the sizes of blocks to be rate matchedmay consequently vary from multiplexing frame to multiplexing frame.Neither is the number k of elements in this list necessarily constant.

As the size Y_(i) associated with the size X_(i) does not depend only onX_(i) but on the entire list (X₁, X₂, . . . , X_(k)) owing to thedynamic matching, it follows that there exists a list (Y₁, Y₂, . . . ,Y_(k)) for each list (X₁, X₂, . . . , X_(k)). The number of lists maytherefore be very large, at least as large as the number of combinationsof transport formats. A transport format combination is a quantitydefining how to demultiplex the multiplexing frame.

Thus, the sending and receiving entities should employ the sameassociation list (X₁, X₂, . . . , X_(k))→(Y₁, Y₂, . . . , Y_(k)). Thesignalling of this list of association between these two entities at thetime of connection of the composite of coded transport channelsrepresents a non-negligible cost in terms of signalling bits. Acomposite of coded transport channels includes at least two groups ofcoded transport channels. Moreover, it would then be necessary toprovide for the exchange of a new list of associations (X₁, X₂, . . . ,X_(k))→(Y₁, Y₂, . . . , Y_(k)) with each addition or removal includedwithin the composite of coded transport channels.

Moreover, the exact matching of the ratio Eb/I depends on the technologyof the channel decoder for each quality of service QoS. The performanceof such a device can vary from one manufacturer to another depending ontheir respective know-how. In fact, this rate matching does not dependon the absolute performance of each decoder, but on their performancerelative to one another, which may therefore vary from one manufacturerto another, if the performance of one of them varies.

It is not therefore possible for the sending and receiving entitiesemployed to be able to “negotiate” the matching of the ratios (Eb/I)through an appropriate exchange of signalling messages.

To explain this, let us imagine two qualities of service A and B, andtwo manufacturers M and N, M and N have the same channel decoder for A,but M has a far more efficient decoder than that of N for B. It is thenclear that manufacturer M could benefit from a smaller ratio Eb/I for Bas this would decrease the total power required and would thereforeproduce a gain in capacity which would enable M to sell more mobiletelecommunication equipments to network operators by arguing thus.

It would therefore be very useful to be able to signal parameters makingit possible to define the rule X→Y for determining the size Y of a blockafter rate matching from the size X of the block before matching. Thiswould make it possible to negotiate or to re-negotiate the proportionsof the ratios Eb/I. This signalling must be as inexpensive as possible.

This adjustment during connection of the ratios Eb/I performed by thehigher levels therefore signifies that if two telecommunication stationsA and B wish to establish or modify a connection over which there is aservice multiplexing, then they follow the following steps:

1. B signals to A what is the maximum load N of a multiplexing frame Bcan send.

2. A determines the ideal proportion for A of the ratios Eb/I from:

-   -   the value of N received from B    -   the maximum puncture rate allowed by A for each quality of        service QoS,    -   the relative demands for each quality of service QoS in terms of        Eb/I    -   the minimum performance demand specified for A.

3. A signals to B what proportion of the ratios Eb/I A expects.

Step 1 is not necessarily present. Systems may be imagined in which themaximum load is known in advance and forms part of the characteristicsof the system. That said, such a system would be highly improbable inview of its lack of flexibility.

It may happen that the proportion of the ratios Eb/I which is determinedby A is sub-optimal in relation to the sought-after aim which is that notransport channel should have more than it deserves. This is acompromise situation in which it is preferred to reduce the capacity ofthe network provided that the connection of the combination of servicescan be established.

Such a compromise is acceptable insofar as the degradation is within thelimits fixed by the minimum performance demand defined in the systemspecification.

It may also happen that the actual tolerance limit is partly at thediscretion of the network. This would make it possible to definenon-guaranteed levels of service, in which the service is provided whenthe traffic conditions so permit, and otherwise it is re-negotiateddownwards.

There will certainly be a specification of possible combinations ofservices. In this specification, for each combination of services, therewill be associated a set of combinations of transport formats. This willdefinitely be the case for the basic services such as the conventionaltelephony service, and all the associated services such as callsignalling, standby, etc.

However, the number of potential combinations may well increase in thefuture, and clear rules will then be needed in order for the higherlevels to determine what combinations are possible, how to negotiatethem, and/or to re negotiate them, and also in order for them todetermine the set of transport format combinations for a givencombination.

The higher levels ought therefore to be able with the aid of simplearithmetic algorithms to determine which combinations of transportformats are possible. To do this, there are at least three arithmeticrules which the higher levels should apply:

-   -   The first rule, concerning channel encoding, makes it possible        to convert the number of elements of the transport blocks sets        and their respective sizes into the number of elements of the        sets of coded blocks and their respective sizes. For example,        this rule may be of the type:        Y=X/(coding rate)+N _(tail), where “coding rate” and “N_(tail)”        are characteristic constants of the code.    -   The second rule concerning segmentation converts the size of a        coded block into the size of a segment produced by the        segmentation per multiplexing frame. In general this rule is a        simple division by F when the transmission interval of the        associated transport channel corresponds to F multiplexing        frames. However, it is not yet clear whether the segmentation is        equal or unequal. In the case of equal segmentation, the coded        blocks have a size which is a multiple of F. In this case, all        the segments are of the same size since there is no rounding        error when dividing by F. In the case of unequal segmentation,        the size of the segment is defined to within 1 bit, on account        of the rounding-up or rounding-down error, and the serial number        of the segment must be known in order to reduce the ambiguity.        For example, if 80 bits are to be segmented into F equal to 8        frames, then all the segments will contain 10 bits and there is        no need to know the serial number of the segment (or position of        the segment) concerned in order to ascertain its size. On the        other hand, if 78 bits are to be segmented into F equal to 8        frames, then 6 segments will contain 8 bits and two other        segments will contain 9 bits and it is necessary to know the        serial number of the segment in order to ascertain its size.    -   The third rule is that which makes it possible to deduce, from        the size X of a block to be rate matched, the size Y of the rate        matched block.

This third rule is not specified and the invention solves this problemof deducing the corresponding sizes for the blocks to be matched.

SUMMARY OF THE INVENTION

The aim of the invention is to ensure that each of the sending andreceiving entities of a mobile telecommunication network can be aware,in a simple manner, for each transport channel associated with one andthe same quality of service, of the size Y of a block obtained at theoutput of the rate matching means and associated with each quality ofservice, as a function of the size X of the block input to the matchingmeans.

The aim of the invention is also to minimize the number of signallingbits making it possible to define, in a manner which is common to thesending and receiving entity or entities, the size Y of a block obtainedat the output of the rate matching means and associated with the size Xof a block input to these rate matching means.

A further aim of the invention is to preserve the flexibility ofdefinition of the association of the sizes Y of blocks output by therate matching means with the sizes X of blocks input to the ratematching means.

To this end, the subject of the invention is a method for a CodeDivision Multiple Access telecommunication system implemented by amobile station, said Code Division Multiple Access telecommunicationsystem implementing a phase of communicating data conveyed by aplurality of transport channels, said Code Division Multiple Accesstelecommunication system comprising at least one base station and atleast said mobile station, said mobile station performing a plurality ofrate matching steps, each of said rate matching steps executing atransformation of an input block of an initial size into an output blockof a final size by puncturing or repeating at least one bit of saidinput block, said method comprising:

receiving a plurality of rate matching parameters from said basestation, each of said plurality of rate matching parameters beingrelative to a rate matching ratio for one of said plurality of transportchannels;

calculating an intermediate size of said output block, for each of saidplurality of transport channels, by multiplying said initial size ofsaid input block by a corresponding rate matching parameter receivedfrom said base station; and

determining, with said mobile station, an available maximum payload fora communication in the Code Division Multiple Access telecommunicationsystem, for at least one radio frame, from among a plurality of possiblemaximum payloads on a basis of a size of a possible maximum payload anda total sum of said intermediate sizes of said output blocks, each ofsaid plurality of possible maximum payloads being relative to at leastone radio frame.

LIST OF FIGURES

The invention will be better understood on reading the description whichfollows, given merely by way of example and with reference to thefollowing drawings in which:

FIG. 1 is a diagrammatic view illustrating the multiplexing of thetransport channels on the uplink in the current 3GPP proposal;

FIG. 2 is a diagrammatic view illustrating the multiplexing of thetransport channels on the downlink in the current 3GPP proposal;

FIG. 3 is a flowchart explaining the implementation of the algorithmaccording to the invention for the downlink; and

FIG. 4 is a flowchart explaining the implementation of the algorithmaccording to the invention for the uplink.

DETAILED DESCRIPTION OF THE INVENTION

Generally, in the invention each quality of service is characterized bytwo integer numbers E and P. E corresponds to the ratio Eb/I, that is tosay if there are several qualities of service labelled 1, 2, . . . , p,whose respective coefficients E are labelled E₁, E₂, . . . , E_(p), thenthe ratios Eb/I of each quality of service will be in the sameproportions as the coefficients E_(i).

The coefficient P corresponds to the maximum puncture rate which isadmissible for a given quality of service. Thus, for each quality ofservice 1, 2, . . . , p, there is associated a maximum puncture ratelabelled P₁, P₂, . . . , P_(p). The maximum puncture rate is imposed bythe channel coding implemented within the processing chain specific tothe relevant quality of service. Puncturing consists in deleting codedbits. This deletion is tolerable insofar as the channel codingintroduces a redundancy. However, the number of punctured bits must notbe too large relative to the total number of bits coded, there istherefore a maximum puncture rate which depends on the channel coding aswell as on the decoder used.

In a telecommunication system, a physical channel dedicated specificallyto the transmission of control data is provided between the varioussending and/or receiving entities of the system. In particular, such achannel exists between the fixed network and the mobile stations of amobile radio communication system. The latter is commonly designated byDPCCH in the 3GPP standard (or Dedicated Physical Control Channel). Itcoexists alongside the physical data transmission channels designatedDPDCH (or Dedicated Physical Data Channel) in this same standard.

According to the invention, to enable each entity of thetelecommunication system to ascertain the set of correspondences betweenthe sizes Y_(i) of the rate matched blocks and the sizes X_(i) of theblocks to be matched and to do so for each quality of service, only thepairs (E_(i), P) with i∈[1,p] are transmitted over the logical controldata transmission channel to all the entities of the system having tocommunicate with one another. These pairs may be established by one ofthe entities or “negotiated” between several entities in a firstembodiment. In a second embodiment, only the parameters (E_(i)) arenegotiated and the parameters (P_(i)) are predefined for a given channelencoding. In a third embodiment, only the parameters (P_(i)) arenegotiated and the set of parameters (E_(i)) is predefined for a givengroup of transport channels. The method for determining thecorrespondences between the sizes of blocks X_(i), Y_(i) from theabove-defined pairs (E_(i), P_(i)) will be described subsequently in thedescription.

Integer numbers are used for E and P since:

-   -   Calculations on integer numbers, or fixed-point calculations,        are simpler to implement, stated otherwise they may be done        faster or with fewer resources;    -   The accuracy of calculations on integer numbers can be very        easily quantified through the number of bits of the registers in        which these integers are stored. Thus, one may easily be assured        that the same rounding errors are produced in the network and in        the mobile station, and hence that the result of the        calculations is exactly the same on either side of the radio        interface.

More precisely, the dynamics are defined as follows:

-   -   E is an integer from 1 to EMAX,    -   P is an integer from 0 to PMAX.

Furthermore, we define the constant PBASE so that PMAX<PBASE, and sothat

$\frac{P}{PBASE}$is the maximum admissible puncture rate for a given quality of PBASEservice.

$\frac{1}{PBASE}$corresponds to the granularity. PBASE is of the order of 10⁴.

The maximum admissible puncture rate

$\frac{P}{PBASE}$for the rate matching step carried out for a given quality of service istypically between 0 and 20%.

Thus, the algorithm of the invention is characterized by 3 integerconstants EMAX, PMAX and PBASE.

In what follows, a fourth integer constant LBASE, concerned with theaccuracy of the calculations, is used.

Let us note that although the same notation EMAX, PMAX, PBASE and LBASEis used for the uplink, that is to say from the mobile station to thenetwork and for the downlink, that is to say from the network to themobile station, the corresponding constants do not necessarily have thesame value in both cases.

Also in what follows, the same notation X and Y is used for the uplinkand for the downlink with different meanings.

Moreover, for each link we shall define a mapping denoted Q in bothcases giving the value of the quality of service QoS for a given indexof a block.

In the downlink, X₁, X₂, . . . , X_(k) denotes the list of possiblesizes before rate matching for the blocks of a given quality of service(QoS), this being for all the possible values of quality of service(QoS).

To be more precise, if the quality of service QoS takes values from 1 top, then:

X_(k) ₀ ₊₁, . . . , X_(k) ₁ are all the possible block sizes for QoS 1

X_(k) _(l) ₊₁, . . . , X_(k) ₂ are all the possible block sizes for QoS2

. . .

X_(k) _(p−1) ₊₁, . . . , X_(k) _(p) are all the possible block sizes forQoS p with the convention that k₀=0 and k_(p)=k and k₀<k₁< . . . <k_(p).

Moreover, we consider a mapping Q from the set {1, . . . , k} of indicesof block sizes for every quality of service QoS to the set of indices{1, . . . , p} of quality of services. We therefore have:

Q: {1, . . . , k}→{1, . . . , p}

-   -   i→Q(i)=j for k_(j−1)<i≦k_(j)

Note that in view of the above definitions, it is possible to have thesame block size twice (X_(i)=X_(j) with i≠j) provided that the qualityof service is not the same (Q(i)≠Q(j)).

For the uplink, the blocks which are to be rate matched for a givenmultiplexing frame are numbered 1, 2, . . . , k and X₁, X₂, . . . ,X_(k) are their respective sizes.

Thus the list (X₁, X₂, . . . , X_(k)) varies from multiplexing frame tomultiplexing frame. Its number k of elements is in particular notnecessarily constant.

Q is a mapping from {1, . . . , k} to {1, . . . , p}, which for therelevant Multiplexing frame, associates with the index i of a block, itsquality of service Q(i).

With this convention, it is possible to have the same block size twice(X_(i)=X_(j) with i≠j) whether or not they have the same quality ofservice (Q(i)=Q(j) or Q(i)≠Q(j)).

Indeed, for two blocks of like quality of service to have the same size,it is sufficient for the channel encoder to output a set of coded blockshaving at least two elements of like size.

To summarize, for the downlink, 1, 2, . . . , k are indices for all thepossible sizes of blocks to be rate matched, given that the block sizescorresponding to different qualities of service are counted separately.For the uplink, 1, 2, . . . , k are the indices of the list of blocks tobe rate matched for a given multiplexing frame.

Y₁, . . . , Y_(k) are the sizes of blocks which correspond respectivelyto X₁, . . . , X_(k) after rate matching.

For the downlink, the algorithm for determining the sets of pairs(X_(i), Y_(i)) from the values E_(q) and P_(q) associated with thequality of service q is illustrated for one and the same processingchain (Q_(d(i))) in FIG. 3 for example for an entity which receives theset of pairs of parameters (E_(q), P_(q)) while negotiating the matchingof the ratios of the average energy of a bit to the average energy ofthe interference (Eb/I). This entity may either be the sending entity(consisting of at least one base station) for the composite of transportchannels, or the receiving entity (consisting of at least one mobilestation) for this composite of transport channels, depending on theentity which decides the result of the current negotiation. In mostcases, it is the receiving entity for the group of transport channelswhich decides and it is the sending entity which implements theconfiguring method of the invention.

Let us assume that for every quality of service q in {1, . . . , p},that is to say for each processing chain, we have the two characteristicintegers E_(q) and P_(q) defined above. These are received in steps 300Aand 300B borne by an already established transport channel.Additionally, the values X_(i) are available, in step 300C, whether theyare predefined for quality of service q, or whether they have beennegotiated.

The first step 302 of the algorithm is to calculate for every q from 1to p an integer parameter L_(q) defined by:

$L_{q} = \left\lfloor \frac{\left( {{PBASE} - P_{p}} \right) \cdot {LBASE}}{E_{q}} \right\rfloor$

where └x┘ represents the largest integer less than or equal to x. It isclear that, according to a variant embodiment, the smallest integergreater than or equal to x is selected.

In general, any other rounding function may be suitable for any step fordetermining a parameter where a rounding function is to be carried out.Furthermore, two steps for determining parameters may use two differentand mutually independent rounding functions.

The next step labelled 304 consists in defining the parameter LMAX by:

${LMAX} = {\max\limits_{q}\left\{ L_{q} \right\}}$

Next, an integer S_(q) is defined in step 306 for every quality ofservice q by:S _(q) =LMAX·E _(q)

S_(q) is such that the rational number

$\frac{Sq}{{PBASE} \cdot {LBASE}}$is the minimum rate matching ratio, given the maximum puncture rate

$\frac{P_{q}}{PBASE}$for each quality of service q.

Stated otherwise, S_(q) must comply with the following relation:

$\frac{S_{q}}{{PBASE} \cdot {LBASE}} \geq {1 - \frac{P_{q}}{PBASE}}$

The configuring method of the invention has the advantage according towhich there is no need in particular within the context of an additionand/or a removal within the current composite of transport channels ofat least one group of transport channels exhibiting the same quality ofservice or within the context of a modification of the ratio of theaverage energy of a bit to the average energy of the interference (Eb/I)which is sought for a given quality of service, to retransmit not theset of pairs of parameters {E_(q), P_(q)}for all the qualities ofservice used, but only the pair(s) of parameters {E_(q),P_(q)}associated with the group(s) of transport channels impacted by theaddition and/or the modification of the ratio (Eb/I) sought.

The preceding part of the algorithm also applies in respect of theuplink. However, the end of the algorithm is specific to the downlink.

On completing step 306, the relation X_(i)→Y_(i) is defined in, step 308by:

$Y_{i} = \left\lceil \frac{S_{Q{(i)}} \cdot X_{i}}{{PBASE} \cdot {LBASE}} \right\rceil$

where ┌x┐ is the smallest integer greater than or equal to x.

Knowing each value of X_(i) and of Y_(i) which correspond, the set ofpairs of sizes (X_(i), Y_(i)) are established in step 310.

To summarize, in the downlink, the algorithm essentially comprises thefollowing four steps.

$\begin{matrix}{{{for}\mspace{14mu}{all}\mspace{14mu}{the}\mspace{14mu}{QoS}\mspace{14mu} q\mspace{14mu}{do}\mspace{14mu} L_{q}} = \left\lfloor \frac{\left( {{PBASE} - P_{p}} \right) \cdot {LBASE}}{E_{q}} \right\rfloor} & \left( {{step}\mspace{20mu} 302} \right)\end{matrix}$

2.

$\begin{matrix}{{L\;{MAX}}:={\max\limits_{q}\left\{ L_{q} \right\}}} & \left( {{step}\mspace{14mu} 304} \right)\end{matrix}$

3. for all the QoS q do Sq:=LMAX·E_(q) (step 306)

4.

$\begin{matrix}{{{for}\mspace{14mu} i}:={{1\mspace{14mu}{to}\mspace{14mu} k\mspace{14mu}{do}\mspace{14mu} Y_{i}} = \left\lceil \frac{S_{Q{(i)}} \cdot X_{i}}{{PBASE} \cdot {LBASE}} \right\rceil}} & \left( {{steps}\mspace{14mu} 308\text{-}310} \right)\end{matrix}$

For the uplink, the algorithm for determining the sets of pairs (X_(i),Y_(j)) from the values E_(q) and P_(q) associated with the quality ofservice q is illustrated for one and the same processing chain(Q_(m(i))) in FIG. 4 for example for an entity which receives the set ofpairs of parameters {E_(q), P_(q)} while negotiating the balancing ofthe ratio of the average energy of a bit to the average energy of theinterference (Eb/I). This entity may either be the sending entity(consisting of at least one base station) for the composite of transportchannels, or the receiving entity (consisting of at least one mobilestation) for this composite of transport channels, depending on theentity which decides the result of the current negotiation. In mostcases, it is the receiving entity for the composite of transportchannels which decides and it is the sending entity which implements theconfiguring method of the invention.

For the uplink, the rate matching ratios are calculated for eachmultiplexing frame. Thus, it is not a question of determining a mappingX_(i)→Y_(i), but rather a mapping (X₁, X₂, . . . , X_(k)) (Y₁, Y₂, . . ., Y_(k)); indeed, the sum of the Y_(i) to Y_(k) must be equal to themaximum payload of a multiplexing frame.

Moreover, the (potential) maximum payload of a multiplexing frame mayvary from frame to frame depending on the physical resources to be usedas a function of the amount of data to be transmitted (corresponding tothe amount of input data for all the sizes X_(i) to X_(k) of the blockstransported). Hence, we can thus define a set {N₁, . . . , N_(r)}with,for example, N₁≦ . . . ≦N_(r) of the possible maximum payloads for themultiplexing frames. More generally, the order 1, 2, . . . r of theindices of N₁, N₂ to N_(r) corresponds to the order of preference of thephysical resources allowing transmission of the various maximum payloads{N₁, N₂, . . . N_(r)}.

Hence, one of the results of the algorithm for determining the ratematching is to select a set, identified by JSEL, of physical resourcesfrom {1, 2, . . . r} allowing transmission of a maximum payload N_(JSEL)and to ensure that:

$\begin{matrix}{{\sum\limits_{i = 1}^{k}\; Y_{i}} = N_{JSEL}} & (1)\end{matrix}$

For this purpose, two successive phases are implemented.

In the first phase, block sizes Y′_(i) are determined “statically” in asimilar manner to the case of the downlink. The steps of this phase aredenoted by the same reference numerals as in FIG. 3 increased by 100.Hence, this is a mapping X_(i)→Y′_(i).

In a second phase, N_(SJEL) and the Y_(i) values corresponding to theY′_(i) values are determined “dynamically” so as to satisfy equation(1). Hence, this is a mapping (Y′₁, Y′₂, . . . Y′_(k))→(Y₁, Y₂, . . . ,Y_(k)).

The first phase consisting of steps 400 to 408 is defined simply by theequation:

Y′_(i)=S_(Q(i))·X_(i).

Next, JSEL is determined in step 410 by the following equation:

${JSEL} = {\min\left\{ {{j/{\sum\limits_{i = 1}^{i = k}\; Y_{j}^{\prime}}} \leq {{PBASE} - {{LBASE} \cdot N_{j}}}} \right\}}$

Stated otherwise, if N₁≦N₂ . . . ≦N_(r), then the smallest maximumpayload allowing transmission is selected.

Then, in step 412 we define integers Z₀, Z₁, . . . , Z_(k) correspondingto the value of the aggregate of the final size by:

Y_(i), that is to say

$Z_{j} = {\sum\limits_{i = 1}^{i = j}\; Y_{i}}$

Z₀:=0

for i:=1 to k do

$Z_{i}:=\left\lfloor \frac{\left( {\sum\limits_{j = 1}^{j = i}\; Y_{j}^{\prime}} \right) \cdot N_{JSEL}}{\sum\limits_{j = 1}^{j = k}\; Y_{j}^{\prime}} \right\rfloor$

where └x┘ is the largest integer less than or equal to x.

Lastly, the Y_(i) are calculated simply in step 414 from:Y _(i) =Z _(i) −Z _(i−1)

In this way, it will be noted that the rounding error in calculating thefinal size (Y_(i)) is not aggregated. Thus, regardless of the number kof data blocks, only two roundings are to be carried out:

a first in respect of the value of the aggregate size denoted Z_(i), and

a second in respect of the value of the previous aggregate size denotedZ_(i−1).

The sought-after pairs (X_(i), Y_(i)) are finally obtained in step 416.

To summarize, in the uplink, the algorithm essentially comprises thefollowing seven steps:

1.

$\begin{matrix}{{{for}\mspace{14mu}{all}\mspace{14mu}{the}\mspace{14mu}{QoS}\mspace{14mu} q\mspace{14mu}{do}\mspace{14mu} L_{q}} = \left\lfloor \frac{\left( {{PBASE} - P_{q}} \right) \cdot {LBASE}}{E_{q}} \right\rfloor} & \left( {{step}\mspace{14mu} 402} \right)\end{matrix}$

2.

$\begin{matrix}{{L\;{MAX}}:={\max\limits_{q}\left\{ L_{q} \right\}}} & \left( {{step}\mspace{14mu} 404} \right)\end{matrix}$

3. for all the Qos q do Sq:=LMAX·E_(q) (step 406)

4. for i:=1 to k do Y′_(i):=S_(Q(i)).X_(i) (step 408)

5.

$\begin{matrix}{{{JSEL} = {\min\left\{ {{j/{\sum\limits_{i = 1}^{i = k}\; Y_{j}^{\prime}}} \leq {{PBASE} - {{LBASE} \cdot N_{j}}}} \right\}}}{Z_{0} = 0}} & \left( {{step}\mspace{14mu} 410} \right)\end{matrix}$

6. for i:=1 to k do for i:=1 to k do

$\begin{matrix}{Z_{i}:=\left\lfloor \frac{\left( {\sum\limits_{j = 1}^{j = i}\; Y_{j}^{\prime}} \right) \cdot N_{JSEL}}{\sum\limits_{j = 1}^{j = k}\; Y_{j}^{\prime}} \right\rfloor} & \left( {{step}\mspace{14mu} 412} \right)\end{matrix}$

7. for i:=1 to k do Y_(i):=Z_(i)−Z_(i−1) (step 414)

To finish let us note that, although the concept of quality of servicehas been defined as the quality of service of a transport channel, thatis to say by the quality of service offered by level 1 to the higherlevels, it would be more correct, given that the object is thedetermination of the rate matching, to speak of the quality of serviceoffered by the bottom of the interleaving and multiplexing chain to thechannel encoder.

The embodiment presented above is not intended to limit the scope of theinvention, and hence numerous modifications may (nevertheless) be madethereto without departing from the context thereof. In particular, itwill be noted that the step for determining the pair of parameters{E_(q), P_(q)} may be performed not only per quality of service, butalso per class of coded bits for one and the same quality of service.Indeed, it is recalled that certain channel encodings (such as inparticular turbocoding) deliver various classes of coded bits which aremore or less sensitive to puncturing.

1. A method for a Code Division Multiple Access telecommunication systemimplemented by a mobile station, said Code Division Multiple Accesstelecommunication system implementing a phase of communicating dataconveyed by a plurality of transport channels, said Code DivisionMultiple Access telecommunication system comprising at least one basestation and at least said mobile station, said mobile station performinga plurality of rate matching steps, each of said rate matching stepsexecuting a transformation of an input block of an initial size into anoutput block of a final size by puncturing or repeating at least one bitof said input block, said method comprising: receiving a plurality ofrate matching parameters from said base station, each of said pluralityof rate matching parameters being relative to a rate matching ratio forone of said plurality of transport channels; calculating an intermediatesize of said output block, for each of said plurality of transportchannels, by multiplying said initial size of said input block by acorresponding rate matching parameter received from said base station;and determining, with said mobile station, an available maximum payloadfor a communication in the Code Division Multiple Accesstelecommunication system, for at least one radio frame, from among aplurality of possible maximum payloads on a basis of a size of apossible maximum payload and a total sum of said intermediate sizes ofsaid output blocks, each of said plurality of possible maximum payloadsbeing relative to at least one radio frame.
 2. The method according toclaim 1, wherein said determining comprises determining, by said mobilestation, a smallest maximum payload, as said available maximum payload,among said plurality of possible maximum payloads.
 3. The methodaccording to claim 1, wherein said determining comprises: selecting aplurality of available maximum payloads; selecting a smallest maximumpayload among said plurality of available maximum payloads; andperforming, by said mobile station, each of said rate matching steps, inaccord with said smallest maximum payload.